SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97b6f4ce51de3144dddf8f4973cc06be2672912bc1c671edbeace20ae53f982b' 
  AND token = '4F3OiKukbeWIyIfN5+ZVbrf673pkOMxBHyBtC4sFfBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}